All scientific theories are "just models"... Leaving theory aside, there is plenty of experimental data showing the quantum behavior of atoms, molecules and smaller particles. Even when QM is disproved, future theory (and other models like simulations) will still need to be consistent with all the experimental evidence showing quantum behavior.

Honestly, as much as I love quantum physics, it truly is amazing how systems that are random and out of place find ways to mimic structure overtime. The fact is that when everything created has this nature, it is incredibly difficult to grasp it. Honestly, this whole thread is just theoretical.

We could in fact be living in a simulation. We could figure out that our conscious can be quantified and we are not special. There is just no way of knowing this due to our current Newtonian system covering only a subset of the way things work. We just don't have a real basis... And regardless of what we say, the fact is that even if we could, it is not something we would be able to comprehend.

The second one actually shows an important concept.If we -ignoring all the problems of computation, space, definitions themselves- can "simulate" our universe this would also include the simulator itself.Best problem explanation for this forum is probably a StackOverflowException.

The second one actually shows an important concept.If we -ignoring all the problems of computation, space, definitions themselves- can "simulate" our universe this would also include the simulator itself.Best problem explanation for this forum is probably a StackOverflowException.

Logically, you can't simulate the universe.If you managed to make a simulator, then the universe would be different - it'd have the simulator in it. You'd have to simulate the universe with the simulator in it simulating the universe which had in it the simulator simulating the simulator simulating the universe... and so on ad infinitum...

Physical rules are written in equations that depends strongly on initial conditions of the system. In classical physics (ie, without quantum mechanics) if you know the initial position and speed of every atom in the universe, that allow you to simulate our universe completely. However, we have two problems:

- Our precision is limited by measurement. I cannot say that this object has coordinate 2 in X axis. It can be on 2.00000 +- 0.00001 position, or even in 2.0000000000 +- 0.0000000001. But that means that our object is somewhere betwen 1.9999999999 and 2.0000000001. There's infinite numbers between that values, so I can't determine the initial position.

- Even if I could manage to obtain the exact initial position of every particle in the universe, remember I left quatum mechanics. If I consider them, then Heisenberg's principle says that it's impossible to know position and speed at the same time.

Of course, I can select random values for initial positions, but that would generate another different universe. To simulate THIS universe I need that positions. And I can't obtain them.

@Roquen I don't see a violation of basic physics in that link. Casimir effect is a well-known quantum effect and it has been proved in labs a lot of times. I don't know if it's useful to build rockets, maybe it isn't. But in principle I can't see wrong physics there =)EDIT: After a deeper research about the experiment, I've confirmed that it violates some conservation laws, so probably the experiment by White has a kind of experimental error.

Short answer: no. You would need at least enough room to store the whole universe a second time to simulate it perfectly. Sorry for my lack of references, I don't remember who explained it the very first time in the history. Drenius and SimonH already explained that a bit better than me.

Short answer: no. You would need at least enough room to store the whole universe a second time to simulate it perfectly. Sorry for my lack of references, I don't remember who explained it the very first time in the history. Drenius and SimonH already explained that a bit better than me.

Now I don't know very much about this topic, but what about compression?

Short answer: no. You would need at least enough room to store the whole universe a second time to simulate it perfectly. Sorry for my lack of references, I don't remember who explained it the very first time in the history. Drenius and SimonH already explained that a bit better than me.

Now I don't know very much about this topic, but what about compression?

The universe can only contain itself, there is just enough room for a single one. If you compress your "copy", it won't change anything because there isn't enough room for 1 universe + 0.000000000000001 universe (your compressed universe). At a certain time, you need the whole uncompressed copy according to Norbert Wiener and Lorenz (see the metaphor of the butterfly: "Predictability: Does the Flap of a Butterfly's Wings in Brazil Set off a Tornado in Texas?"), some "small" causes can have "big" effects (see Chaos Theory).

You can make a manageable simulation by using a pseudo-isolated simplified part of the universe but it is less faithful to the reality. I assume this is what ags1 meant, am I completely wrong?

Tons of things have been written about predictability, especially by Cauchy, Laplace, Poincaré, Lipschitz, Lyapounov, Von Neumann, ...

Short answer: no. You would need at least enough room to store the whole universe a second time to simulate it perfectly. Sorry for my lack of references, I don't remember who explained it the very first time in the history. Drenius and SimonH already explained that a bit better than me.

Yes, Drenius and SimonH already explained. And when I first created the Topic, I didn't have the simulation of our instance of our universe in mind, but the simulation of a universe with the same rules as ours (but it can have other initial conditions).

My question in my mind that seems like can't yet be answered is: Is our universe deterministic? Do the same initial conditions result in the same universe?

What do you mean by "that initial conditions"? The initial conditions of our universe? I don't want to.

Knowing that we can simulate a universe that is (maybe) similar to ours (has the same rules) and (maybe) also has intelligent life like ours opens new possibilities for arguing in a philosophical way to the question: "What is love life?" It means we could create life just like ours in a computer. It makes defining life and killing much harder. Is turning of the simulating computer killing/murder?

My question in my mind that seems like can't yet be answered is: Is our universe deterministic? Do the same initial conditions result in the same universe?

Nobody can answer these two questions. Until we have a perfect model it's just guessing. Even then the answers will probably be unknowable. It seems to me that it's more likely that the universe is deterministic but it's a too depressing a thought to think about too much.

Given that so many of the observed constants are required for life (as we know it) I wonder if perhaps the size of the universe is important..in that any small change in it would cause nothing to work as it does.

I don't see a violation of basic physics in that link. Casimir effect is a well-known quantum effect and it has been proved in labs a lot of times. I don't know if it's useful to build rockets, maybe it isn't. But in principle I can't see wrong physics there =)

So I did a web-search to see what someone with a real clue might have to say

Good links. I also did a deeper research and effectively looks like the results obtained are wrong, or there's a lot of new things in that experiment. Most sources agree that looks like first option xDHowever, I want to point that forces origined by quantum vacuum (Casimir effect) is proven. This guy is using a different thing called "dynamic Casimir effect" which is not completely proven by now I think. You can take a look in wikipedia:http://en.wikipedia.org/wiki/Casimir_effect

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What do you mean by "that initial conditions"? The initial conditions of our universe? I don't want to.

Knowing that we can simulate a universe that is (maybe) similar to ours (has the same rules) and (maybe) also has intelligent life like ours opens new possibilities for arguing in a philosophical way to the question: "What is love life?" CheesyIt means we could create life just like ours in a computer. It makes defining life and killing much harder. Is turning of the simulating computer killing/murder?

I meant initial conditions of our universe, yes. It's difficult to simulate a "similar" universe like ours, I think. Result diverge from initial conditions so from initial conditions close to our universe we can find a very different one.But, yes, if you want to design a random universe, it's like create a new map in Minecraft: give initial conditions (seed) and run the software, you'll get a new universe.

Ah, I forgot last time... There's a simulation of the universe formation, it's called project Illustris. The objective was determine how galaxies are formed and dark matter distribution. It astonishing to see that the galaxies formed in the simulation (from different initial conditions) are very, VERY similar to the galaxies we can see in our universe.Here is the link: http://www.illustris-project.org/

So, the argument seems to be: "You can't simulate the universe because this universe would have to contain itself and another (simulated) universe, which won't fit."

Is that true? For example, can our universe simulate a very simple universe consisting of say 1 electron and nothing else? You might say yes, eventually we could, but then... "You can't simulate even a tiny universe, because this universe would have to contain itself and an additional (simulated) universe, which won't fit."

So by that line of reasoning, you can't simulate anything at all. It explains why my sim games never seem to work :-) They can't fit in the universe!

My argument is that it's effectively uncomputable. The system in the system argument is also valid. A simply analogy is that you can build a computer in "the game of life". Which in turn can run it, but only at a smaller scale than itself. etc.

My argument is that it's effectively uncomputable. The system in the system argument is also valid. A simply analogy is that you can build a computer in "the game of life". Which in turn can run it, but only at a smaller scale than itself. etc.

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